This specialized research center with more than 10,000 patients on file with retinitis pigmentosa proposes a clinical trial to determine whether a nutritional supplement will slow the course of the common forms of retinitis pigmentosa. Two hundred and eleven patients who meet a preset list of eligibility criteria will be randomly assigned to either a treatment or a control group and followed annually over a period of 5 years. All patients will receive 15,000 IU/day of vitamin A palmitate. Static perimetric thresholds measured with a Humphrey Field Analyzer will be used as the primary outcome measure. Electroretinograms, visual acuities, and assessment of quality of life will be monitored as secondary outcome measures. The study will be conducted with a double-masked protocol. Collaborative arrangements have been made for biochemical analyses with Tufts University School of Medicine and Brandeis University.